CN112398772A - OFDM system reception demodulation method and OFDM system receiver - Google Patents
OFDM system reception demodulation method and OFDM system receiver Download PDFInfo
- Publication number
- CN112398772A CN112398772A CN201910747661.3A CN201910747661A CN112398772A CN 112398772 A CN112398772 A CN 112398772A CN 201910747661 A CN201910747661 A CN 201910747661A CN 112398772 A CN112398772 A CN 112398772A
- Authority
- CN
- China
- Prior art keywords
- sub
- subframe
- frame
- channel estimation
- decoding
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2649—Demodulators
- H04L27/265—Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
- H04L27/2695—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with channel estimation, e.g. determination of delay spread, derivative or peak tracking
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Discrete Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
The invention provides a receiving and demodulating method of an OFDM system and a receiver of the OFDM system, which are characterized by comprising the following steps: receiving service layer information and physical layer signaling to perform decoding subframe control; and the decoding subframe control is used for judging the subframe where the current data of the user is located and outputting the subframe indication needing decoding to perform channel estimation, so that the subframe switching of different FFT sizes is continuously and stably performed under the condition that the buffer space is not increased when scenes are switched according to different subframe sizes, no extra error code is introduced, and the watching experience of the user is not influenced.
Description
Technical Field
The present invention relates to OFDM system receiving and demodulating technology, and in particular, to an OFDM system receiving and demodulating method and channel estimation, synchronization, and equalization technology in a receiver.
Background
ATSC3.0 is a new generation digital broadcast television standard in the united states and is currently being commercialized. The system corresponding to the standard is an advanced terrestrial digital broadcast television transmission system based on an OFDM air interface technology. The system adopts a plurality of new technologies in the wireless communication and broadcasting fields, such as LDM layered multiplexing, more advanced LDPC coding, Non-uniform constellation mapping and the like. Due to the application of the new technologies, the ATSC3.0 system has more efficient spectrum utilization rate and more flexible application scenes while the robustness is ensured.
Among new technologies adopted by a series of ATSC3.0 systems, a multi-subframe flexible configuration technology provides great help for expanding the application scene of the ATSC3.0 system.
Future ATSC3.0 system signals are expected to be received by both fixed (e.g., television) and mobile (e.g., vehicle television, cell phone, etc.) devices. The multi-subframe flexible configuration technology can set a plurality of subframes with different parameters in one ATSC3.0 physical frame, and the subframes can configure parameters such as different FFT sizes, GI lengths and the like. Because the size of the FFT corresponds to the interval of the sub-carriers, when the OFDM symbol in a sub-frame has larger FFT size (such as 32K), the interval of the sub-carriers is smaller, the utilization rate of the frequency spectrum is higher, and the method is suitable for fixed receiving requiring high transmission rate; when the OFDM symbol in a subframe has a smaller FFT size (e.g., 8K), the subcarrier spacing is larger, the spectrum utilization is lower, but the doppler spread can be resisted more, and the method is suitable for mobile reception requiring high robustness. Therefore, by using the multi-subframe flexible configuration technology, in one ATSC3.0 physical frame, a plurality of subframes with different FFT sizes are combined, and the coexistence of fixed reception and mobile reception can be supported with lower signaling overhead. The physical frame structure of the ATSC3.0 system, and the flexible configuration of multiple subframes, are shown in fig. 1.
Fig. 1 is a diagram illustrating a configuration of multiple subframes in an ATSC3.0 physical frame structure in the related art. As can be seen from FIG. 1, the physical frame comprises preamble symbols, signaling symbols and a plurality of subframes, for example, subframe 0 is set to 32k FFT and subframe n-1 is set to 8k FFT.
On the other hand, fig. 2 is a block diagram of a typical receiver of an OFDM system in the prior art. The receiver of an OFDM system often has a structure as shown in fig. 2.
The receiver of the OFDM system comprises: the device comprises a deviation adjusting module, an FFT (fast Fourier transform) module, a channel estimation module, a multipath detection module, a frequency offset/time offset estimation module and a balancing module. Through the modules, the time domain received signal R is transformed into the frequency domain OFDM received symbol R through FFT. And the channel estimation module obtains an estimated value H of the frequency domain channel impulse response by utilizing R, and sends R and H to a subsequent equalization module to obtain an estimated value X of the transmitted signal. Meanwhile, H output by channel estimation also often acts on a multipath detection module and a frequency offset and time offset estimation module, multipath information output by the multipath detection module is used for filtering the channel estimation module, and estimation results output by the frequency offset and time offset estimation module are used for adjusting the offset of the front end of the receiver.
In the ATSC3.0 system, due to the characteristic of discrete distribution of pilots, the ATSC3.0 receiver comprises the following steps when performing channel estimation:
the method comprises the following steps: performing least square estimation on the pilot frequency position to obtain an initial channel estimation result on the pilot frequency position;
step two: increasing the density of an initial channel estimation value on the current OFDM symbol by using a time domain interpolation method;
step three: and obtaining channel estimation results of all subcarriers by utilizing all initial channel estimation results on the current OFDM symbol through frequency domain interpolation.
And with the difference of the pilot intervals in the time domain, in order to implement the time domain interpolation described in step two, the channel estimation module often needs to buffer the OFDM symbols of different numbers backwards.
For example, in the ATSC3.0 standard, the time-domain pilot interval is defined as a parameter Dy, and Dy is fixed to be 2 in 32K FFT size, and Dy may be 4 or 2 in 8K FFT size. Therefore, to minimize the symbol buffer amount, the channel estimation usually buffers a different number of symbols backwards for different FFT sizes. Fig. 3 and 4 are schematic diagrams of channel estimation time-domain interpolation in the prior art with 32K FFT size (Dy ═ 2) and 8K FFT size (Dy ═ 4). For example, when 32K FFT size, the channel estimate buffers 1 OFDM symbol backward; while when 8K FFT size, the channel estimate is buffered 3 OFDM symbols backward. Taking 32K FFT size, Dy being 2 as an example, the channel estimation time domain interpolation process is shown in fig. 3, and taking 8K FFT size, Dy being 4 as an example, the channel estimation time domain interpolation process is shown in fig. 4. As can be seen from fig. 3, the time-domain interpolation of the channel estimation needs to be delayed by one symbol for 32K FFT size, and as can be seen from fig. 4, the time-domain interpolation of the channel estimation needs to be delayed by 3 symbols for 8K FFT size. It can be known from fig. 3 and fig. 4 that the number of symbol delays for channel estimation time domain interpolation is different for different FFT sizes.
When all the sub-frames in the ATSC3.0 physical frame are configured to have the same FFT size, the channel estimation module only needs to continuously buffer symbols according to the fixed number of buffered symbols and perform time domain interpolation. However, when there are subframes of different FFT sizes in an ATSC3.0 physical frame, the technical problem faced becomes more complex. Because at the boundary of the sub-frame, when the FFT size changes abruptly, the rhythm of the channel estimation output symbols is disturbed due to the different number of the symbols buffered backward.
As follows, when there are subframes with different FFT sizes, assuming that the number of channel estimation delay symbols is n for a subframe with a larger FFT size, and m for a subframe with a smaller FFT size. At present, the following two schemes for dealing with the subframe switching scenes with different FFT sizes are mainly adopted:
1. the first scheme is as follows: the sub-frames with the respective FFT sizes are still according to respective original delay schemes, so that when the received signals are switched from the sub-frames with the larger FFT sizes to the sub-frames with the smaller FFT sizes, the channel estimation module outputs m-n symbols later; when the received signal is switched from a subframe with a smaller FFT size to a subframe with a larger FFT size, the channel estimation loses the output of m-n symbols. The advantage of this scheme is that the delay of the data to the decoder (time delay) is not significantly jittery without adding extra storage. The disadvantage is that when the received signal is switched from the subframe with smaller FFT size to the subframe with larger FFT size, missing symbols will fixedly introduce decoding failure of a part of code blocks, which seriously affects user experience.
2. And scheme II: and (4) unifying t to 3(t is the maximum number of symbol delays corresponding to the channel estimation when the FFT size is 8K). The advantages are that no performance loss occurs, but the delay memory (definition) of the received data (definition) is significantly increased (about 3 times larger than the original), and the time delay of the data arriving at the decoder is jittered (the symbol delay is fixed, but the symbol intervals are different for different FFT sizes).
One of the two schemes is that the buffer space is not increased, but extra error codes are introduced to influence the watching experience of a user; and the other method does not affect the viewing experience of the user, but additionally increases the cache space and increases the cost of the terminal chip.
Disclosure of Invention
The invention aims to provide an OFDM system receiving demodulation method and an OFDM system receiver, which can continuously and stably switch subframes with different FFT sizes without increasing buffer space during channel estimation time domain interpolation, do not introduce extra error codes and do not influence the watching experience of users.
In order to achieve the above object, the present invention provides a receiving and demodulating method for an OFDM system, comprising the steps of: receiving service layer information and physical layer signaling to perform decoding subframe control; and the decoding subframe control is used for judging the subframe where the current data of the user is located and outputting the subframe indication needing to be decoded for channel estimation.
In the OFDM system receiving and demodulating method provided in the present invention, further, the method may further have a feature that the channel estimation has the following time domain interpolation step: determining the sub-mode to be entered according to the indication of the current decoding sub-frame and the FFT size relation of the sub-frames before and after the sub-frame during switching; respectively carrying out time domain interpolation according to the current sub-mode; and outputting the time domain interpolation result to carry out the next processing to obtain the final channel estimation result.
In the OFDM system receiving and demodulating method provided in the present invention, further, the method may further include determining a sub-mode to be entered according to an indication of a currently decoded subframe and an FFT size relationship of subframes before and after the subframe at the time of switching, including: when the FFT small subframe is switched to the FFT large subframe and the decoding subframe is indicated as a small subframe, a first decoding subframe control sub-mode is entered; when the FFT small sub-frame is switched to the FFT large sub-frame and the decoding sub-frame is indicated to be the large sub-frame, a second decoding sub-frame control sub-mode is entered; when the FFT large sub-frame is switched to the FFT small sub-frame and the decoding sub-frame is indicated to be a large sub-frame, a third decoding sub-frame control sub-mode is entered; and entering a fourth decoding subframe control sub-mode when the FFT large subframe is switched to the FFT small subframe and the decoding subframe is indicated to be a small subframe.
In the OFDM system reception/demodulation method according to the present invention, further, the first decoding subframe control sub-pattern may include: in the FFT sizes of the subframes before and after the subframe during switching, the number of the channel estimation delay symbols of the smaller subframe is m, the channel estimation delay symbols of the larger subframe is n, the first m symbols of the larger subframe do not participate in the channel estimation time domain interpolation calculation of the last m symbols of the smaller subframe, and the channel estimation module discards the first m-n symbols of the larger subframe during output.
In the OFDM system reception/demodulation method according to the present invention, the second decoding subframe control sub-pattern may further include: in the FFT subframe sizes before and after the subframe during switching, the number of the channel estimation delay symbols of the smaller subframe is m, the channel estimation delay symbols of the larger subframe is n, the first n symbols of the larger subframe do not participate in channel estimation time domain interpolation calculation of the last n symbols of the smaller subframe, and the channel estimation module discards the last m-n symbols of the smaller subframe during output.
In the OFDM system reception/demodulation method according to the present invention, further, the OFDM system reception/demodulation method may further include a third decoding subframe control sub-pattern including: in the FFT subframe sizes before and after the subframe during switching, the number of channel estimation delay symbols of a larger subframe is n, the number of channel estimation delay symbols of a smaller subframe is m, the first n symbols of the subframe with the smaller FFT size do not participate in channel estimation time domain interpolation calculation of the last n symbols of the subframe with the larger FFT size, and a channel estimation module delays m-n symbols at the beginning of the smaller subframe during output.
In the OFDM system reception/demodulation method according to the present invention, further, the method may further include a step in which the fourth decoding subframe control sub-pattern includes: in the FFT subframe sizes before and after the subframe during switching, the channel estimation delay symbol number of the larger subframe is n, the channel estimation delay symbol of the smaller subframe is m, the first n symbols of the subframe with the smaller FFT size and the channel estimation time domain interpolation calculation of the last n symbols of the subframe with the larger FFT size are selected to be output or not output.
In the OFDM system reception/demodulation method according to the present invention, further, the method may further include a step of replacing a subframe boundary symbol before and after the subframe at the time of switching according to a subframe to be currently decoded.
In the OFDM system reception and demodulation method provided in the present invention, further, the method may further include: and according to the output symbol result of the channel estimation module, balancing the corresponding symbol to balance each symbol of the subframe to be decoded, thereby ensuring the continuity of subsequent decoding.
In addition, the present invention provides an OFDM system receiver, comprising: the system comprises a decoding subframe control module and a channel estimation module, wherein service layer information and physical layer signaling are input into the decoding subframe control module, and the decoding subframe control module is used for judging a subframe where user current data is located and outputting a subframe indication needing decoding to the channel estimation module.
In the OFDM system receiver provided in the present invention, further, the OFDM system receiver may further have a feature that the channel estimation module is configured to perform time domain interpolation: determining the sub-mode to be entered according to the indication of the current decoding sub-frame and the size relation of the sub-frames before and after the sub-frame during switching; respectively carrying out time domain interpolation according to the current sub-mode; and outputting the time domain interpolation result to carry out the next processing to obtain the final channel estimation result.
In the OFDM system receiver according to the present invention, further, the OFDM system receiver may further include: the system comprises a deviation adjusting module, an FFT (fast Fourier transform) module, a channel estimation module, a multipath detection module, a frequency/time offset estimation module and an equalization module, wherein a known time domain received signal R is transformed into a frequency domain OFDM (orthogonal frequency division multiplexing) received symbol R through FFT, the channel estimation module obtains an estimated value H of frequency domain channel impulse response by utilizing R, the R and the H are sent to the subsequent equalization module to obtain an estimated value X of a transmitted signal and an estimated value H output by channel estimation, the estimated value H is used for the multipath detection module and the frequency/time offset estimation module, multipath information output by the multipath detection module is used for filtering the channel estimation module, and an estimation result output by the frequency/time offset estimation module is used for deviation adjustment of the front end of a receiver.
Action and Effect of the invention
The OFDM system receiving and demodulating method and the OFDM system receiver can be better applied to a channel estimation and synchronous equalization technology under the scene of switching subframes with different FFT sizes, which is described in the American new generation broadcast television standard ATSC3.0, can continuously and stably switch subframes with different FFT sizes without increasing buffer space, and do not introduce extra error codes and influence the watching experience of users.
Drawings
Fig. 1 is a diagram illustrating a configuration of multiple subframes in an ATSC3.0 physical frame structure in the related art.
Fig. 2 is a block diagram of a typical receiver of an OFDM system in the prior art.
Fig. 3 is a schematic diagram of 32K FFT size (Dy ═ 2) channel estimation time-domain interpolation in the prior art.
Fig. 4 is a schematic diagram of a time-domain interpolation of 8K FFT size (Dy ═ 4) channel estimation in the prior art.
Fig. 5 is a block diagram of a receiver of an OFDM system according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating control of input/output symbols for channel estimation in a first decoding sub-frame control sub-mode according to an embodiment of the present invention.
FIG. 7 is a diagram illustrating control of input/output symbols for channel estimation in a second decoding sub-frame control sub-mode according to an embodiment of the present invention.
FIG. 8 is a diagram illustrating control of input/output symbols for channel estimation in a third decoding sub-frame control sub-mode according to an embodiment of the present invention. And
FIG. 9 is a diagram illustrating control of input/output symbols for channel estimation in a fourth decoding sub-frame control sub-mode according to an embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
In the ATSC3.0 system, a transmitter may transmit two subframes with different FFT sizes in one physical frame, but because the two subframes correspond to different service types, only one of the subframes needs to be received at a certain receiver at the same time. By utilizing the characteristic of the receiver, a decoding subframe control module can be added on the basis of the original receiver structure, and the logic control function in channel estimation is strengthened.
Fig. 5 is a block diagram of a receiver of an OFDM system according to an embodiment of the present invention. As shown in fig. 5. On the basis of fig. 2, the receiver of the OFDM system includes an offset adjustment module, an FFT transformation module, a channel estimation module, a multipath detection module, a frequency/time offset estimation module, and an equalization module. The OFDM system receiver of the invention is additionally provided with a decoding subframe control module, information obtained from a service layer, namely service layer information (for example, which path of data is watched by a user) and a physical layer signaling result, namely a physical layer signaling (for example, which subframe each path of data is in respectively) are taken as input and input into the decoding subframe control module, the decoding subframe control module is used for judging which subframe the data watched by the user is positioned in and outputting the subframe number as a subframe indication needing to be decoded to a channel estimation module.
The enhanced channel estimation module performs internal time domain interpolation, and channel estimation newly-added according to the output of the decoding subframe control module, and comprises the following processing steps:
step one, a channel estimation module determines a sub-mode to be entered for processing according to the indication of a current decoding subframe and the relation between the front and the back of the subframe during switching.
The decoding subframe control module gives a subframe indication needing decoding according to information (which path of data a user watches) given by a current service layer and a physical layer signaling result (which subframe each path of data is in), and transmits the indication to the channel estimation module.
And step two, the channel estimation module determines a processing branch according to the indication of the current decoding subframe and the relation between the front and the back of the subframe during switching. In this embodiment, two subframes, 8K FFT Size and 32K FFT Size, are used for illustration.
If the current FFT subframe Size is switched from small to large, and the decoding subframe control module indicates that the FFT Size is small, for example, if the current FFT subframe Size is 8K to 32K, and the subframe of 8K FFT Size needs to be decoded, branch 1 is entered, i.e., the first decoding subframe control sub-mode is entered.
If the current FFT subframe Size is switched from small to large, and the decoding subframe control module indicates that the FFT Size is large, for example, if the current FFT subframe Size is 8K to 32K, and the subframe of 32K needs to be decoded, branch 2 is entered, i.e., the second decoding subframe control sub-mode is entered.
If the current FFT subframe Size is switched from large to small, and the decoding subframe control module indicates that the FFT Size is large, for example, if the current FFT subframe Size is 32K to 8K, and the subframe of 32K FFT Size needs to be decoded, branch 3 is entered, i.e., the third decoding subframe control sub-mode is entered.
If the current FFT subframe Size is switched from large to small, and the decoding subframe control module indicates that the FFT Size is small, for example, if the current FFT subframe Size is 32K to 8K, and the subframe of 8K needs to be decoded, branch 4 is entered, i.e., the fourth decoding subframe control sub-mode is entered.
And step three, the time domain interpolation module of the channel estimation respectively processes according to the current processing branch, namely according to the current branch, namely the branch mode:
in this embodiment, the larger and smaller of the subframe with larger FFT size and the subframe with smaller FFT size mean that the sizes before and after the subframe switching are relatively larger and smaller, and detailed description is omitted.
[ BRANCH 1 ]
And setting the number of the channel estimation delay symbols of the subframe with smaller FFT size as m, and the channel estimation delay symbols of the subframe with larger FFT size as n, so as to ensure the continuity of the channel estimation result of the decoding subframe with smaller FFT size. The first m symbols of the subframe with larger FFT size do not participate in the channel estimation time domain interpolation calculation of the last m symbols of the subframe with smaller FFT size. Therefore, when outputting, the channel estimation module discards the first m-n symbols of the sub-frame with larger FFT size.
FIG. 6 is a diagram illustrating control of input/output symbols for channel estimation in a first decoding sub-frame control sub-mode according to an embodiment of the present invention.
As shown in fig. 6, if the subframe with smaller FFT size is 8K FFT size and the subframe with larger FFT size is 32K FFT size, the dashed line of the input symbol represents that the time domain interpolation is not involved.
Since the channel estimation delay symbol of the 8K subframe is m-3, and the channel estimation delay symbol of the 32K subframe is n-1, in order to ensure the continuity of the 8K decoding subframe, the input symbols No. 2, 3 and 4 (corresponding to the first three symbols of the 32K subframe, where the first m-3 symbols) do not participate in the time domain interpolation calculation of channel estimation (i.e. represented by dotted arrows), and the output symbols No. 2, 3 and 4 (corresponding to the last three symbols of the 8K subframe, where the last m-3 symbols) do not participate in the time domain interpolation, and when performing the time domain interpolation, the one-way interpolation is performed by using only the least square result of the previous symbols. It can be seen that the channel estimation module discards the first two symbols of the 32K subframe, i.e. m-n is 2, when outputting.
[ BRANCH 2 ]
And setting the number of the channel estimation delay symbols of the subframe with smaller FFT size as m, and the channel estimation delay symbols of the subframe with larger FFT size as n, so as to ensure the continuity of the channel estimation result of the decoding subframe with larger FFT size. The first n symbols of the sub-frame with larger FFT size do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the sub-frame with smaller FFT size. Therefore, the channel estimation module discards the last m-n symbols of the sub-frame with smaller FFT size when outputting.
FIG. 7 is a diagram illustrating control of input/output symbols for channel estimation in a second decoding sub-frame control sub-mode according to an embodiment of the present invention.
As shown in fig. 7, if the subframe with smaller FFT size is 8K FFT size and the subframe with larger FFT size is 32K FFT size, the dashed line of the input symbol represents that the time domain interpolation is not involved.
Since the channel estimation delay symbol of the 8K subframe is m-3 and the channel estimation delay symbol of the 32K subframe is n-1, in order to ensure the continuity of the 32K decoding subframe, the input and output symbol control of the channel estimation is as shown in fig. 7. The input symbol No. 2 (corresponding to the first symbol of the 32K subframe, where the first n is 1 symbol) does not participate in the time-domain interpolation calculation of the channel estimation (i.e., indicated by a dotted arrow), and the output symbol No. 2 (corresponding to the third last symbol of the 8K subframe) performs the unidirectional interpolation by using only the least square result of the previous symbol when performing the time-domain interpolation. It can be seen that the channel estimation module discards the last two symbols of the 8K subframe, i.e. discards the last m-n-2 symbols at the output.
[ Branch 3: "C (B)
The number of channel estimation delay symbols of a subframe with a large FFT size is set to be n, and the number of channel estimation delay symbols of a subframe with a small FFT size is set to be m. The continuity of the channel estimation result of the decoding subframe with larger FFT size is ensured. The first n symbols of the subframe with smaller FFT size do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the subframe with larger FFT size. Therefore, when the channel estimation module outputs, m-n symbols are output at the beginning of the subframe with smaller FFT size by a plurality of delays.
FIG. 8 is a diagram illustrating control of input/output symbols for channel estimation in a third decoding sub-frame control sub-mode according to an embodiment of the present invention.
As shown in fig. 8, if the subframe with smaller FFT size is 8K FFT size and the subframe with larger FFT size is 32K FFT size, the dashed line of the input symbol represents that the time domain interpolation is not involved.
Since the channel estimation delay symbol of the 32K subframe is n-1 and the channel estimation delay symbol of the 8K subframe is m-3, in order to ensure the continuity of the 32K decoding subframe, the input and output symbol control of the channel estimation is as shown in fig. 8. The input symbol No. 3 (corresponding to the first symbol of the 8K subframe, where the first n is 1 symbol) does not participate in time domain interpolation calculation for channel estimation (i.e., indicated by a dotted arrow), and the output symbol No. 3 (corresponding to the last symbol of the 32K subframe, where the last n is 1 symbol) performs unidirectional interpolation by using only the least square result of the previous symbol when performing time domain interpolation. It can be seen that, when outputting, the channel estimation module delays the output by 2 symbols at the beginning of the 8K subframe, that is, there is no corresponding output symbol for the input symbols 4 and 5.
[ BRANCH 4 ]
The number of channel estimation delay symbols of a subframe with a large FFT size is n, the number of channel estimation delay symbols of a subframe with a small FFT size is m, and in order to ensure the continuity of a decoding subframe with a small FFT size, the channel estimation processing process of the branch 4 is basically the same as that of the branch 3, namely, the first n symbols of the subframe with the small FFT size do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the subframe with the large FFT size, and the last n symbols of the subframe with the large FFT size can be selectively output or not output.
Here, the branch 3 and the branch 4 differ only here: for the last n symbols of the sub-frame with larger FFT size, since only one-way interpolation is performed, and the sub-frame with larger FFT size is not a decoded sub-frame, it can be selected to output or not output (here, the non-dotted line, that is, the circle broken line indicates).
FIG. 9 is a diagram illustrating control of input/output symbols for channel estimation in a fourth decoding sub-frame control sub-mode according to an embodiment of the present invention.
As shown in fig. 9, for the branch 4, since the channel estimation delay symbol of the 32K subframe is n-1 and the channel estimation delay symbol of the 8K subframe is m-3, to ensure the continuity of the 8K decoding subframe, the symbol control of the branch 4 is similar to the branch 3 as a whole, and the input symbol No. 3 (corresponding to the first symbol of the 8K subframe, where n is 1 symbol) does not participate in the time domain interpolation calculation of the channel estimation (i.e., indicated by a dotted arrow). The difference is that for the 3 rd output symbol (corresponding to the last symbol of the 32K subframe, where the last n is 1 symbol), only one-way interpolation is performed, and the 32K subframe is not a decoded subframe, so that the output may be selected or not selected.
And step four, outputting a time domain interpolation result to perform next processing to obtain a final channel estimation result. The method comprises the steps of multipath detection, frequency offset and time offset estimation, and necessary processing is carried out by a frequency offset and time offset estimation module according to an output time domain interpolation result of channel estimation.
In this embodiment, the method may further include the following step: and the equalization module performs equalization processing on the corresponding symbol according to the output symbol result of the channel estimation module. Each symbol of the sub-frame to be decoded is equalized, and the continuity of subsequent decoding is guaranteed.
By the above description of branch 1 to branch 4, it is understood that the time domain interpolation can be understood as using the result of the symbols located in the following time domain to estimate the position of the space of the symbols located in the preceding. The problem with subframe switching is to consider how to take subframe boundary symbols off, depending on the subframe currently to be decoded.
Further referring to the structural diagram of fig. 5, it can be seen that, in the present invention, a part is added with a decoding subframe control module, and a part is added with logic control at the time domain interpolation of channel estimation. The second step and the third step are realized by a channel estimation module and are not realized by a decoding subframe control module.
Those skilled in the art will recognize that the foregoing description is merely one or more embodiments of the present invention, and is not intended to limit the invention thereto. Any equivalent changes, modifications and equivalents of the above-described embodiments are within the scope of the invention as defined by the appended claims, and all such equivalents are intended to fall within the true spirit and scope of the invention.
Claims (12)
1. A method for receiving and demodulating OFDM system, comprising the steps of:
receiving service layer information and physical layer signaling to perform decoding subframe control; and
and the decoding subframe control is used for judging the subframe where the current data of the user is located and outputting a subframe indication needing to be decoded for channel estimation.
2. The OFDM system reception demodulation method as claimed in claim 1, comprising:
the channel estimation has the following time domain interpolation steps:
determining the sub-mode to be entered according to the indication of the current decoding sub-frame and the FFT size relation of the sub-frames before and after the sub-frame during switching;
respectively carrying out time domain interpolation according to the current sub-mode; and
and outputting a time domain interpolation result to perform next processing to obtain a final channel estimation result.
3. The OFDM system reception demodulation method as claimed in claim 1, comprising:
wherein, the determining the sub-mode to be entered according to the indication of the current decoding sub-frame and the FFT size relationship of the sub-frames before and after the sub-frame during switching comprises:
when the FFT small subframe is switched to the FFT large subframe and the decoding subframe is indicated as a small subframe, a first decoding subframe control sub-mode is entered;
when the FFT small sub-frame is switched to the FFT large sub-frame and the decoding sub-frame is indicated to be the large sub-frame, a second decoding sub-frame control sub-mode is entered;
when the FFT large sub-frame is switched to the FFT small sub-frame and the decoding sub-frame is indicated to be a large sub-frame, a third decoding sub-frame control sub-mode is entered; and
and when the FFT large sub-frame is switched to the FFT small sub-frame and the decoding sub-frame is indicated to be the small sub-frame, entering a fourth decoding sub-frame control sub-mode.
4. The OFDM system reception demodulation method as claimed in claim 1, comprising:
wherein the first decoding subframe control sub-pattern comprises:
in the FFT sizes of the sub-frames before and after the sub-frame during switching, the number of the channel estimation delay symbols of the smaller sub-frame is m, the number of the channel estimation delay symbols of the larger sub-frame is n,
the first m symbols of the larger sub-frame do not participate in the channel estimation time domain interpolation calculation of the last m symbols of the smaller sub-frame,
and when outputting, the channel estimation module discards the first m-n symbols of the larger subframe.
5. The OFDM system reception demodulation method as claimed in claim 1, comprising:
wherein the second decoding subframe control sub-pattern comprises:
in the FFT sub-frame sizes before and after the sub-frame during switching, the channel estimation delay symbol number of the smaller sub-frame is m, the channel estimation delay symbol of the larger sub-frame is n,
the first n symbols of the larger sub-frame do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the smaller sub-frame,
the channel estimation module discards the last m-n symbols of the smaller sub-frame at the output.
6. The OFDM system reception demodulation method as claimed in claim 1, comprising:
wherein the third decoding subframe control sub-pattern comprises:
in the FFT sub-frame sizes before and after the sub-frame during switching, the channel estimation delay symbol number of the larger sub-frame is n, the channel estimation delay symbol of the smaller sub-frame is m,
the first n symbols of the sub-frame with smaller FFT size do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the sub-frame with larger FFT size,
the channel estimation module delays m-n symbols at the beginning of a smaller sub-frame when outputting.
7. The OFDM system reception demodulation method as claimed in claim 1, comprising:
wherein the fourth decoding subframe control sub-pattern comprises:
in the FFT sub-frame sizes before and after the sub-frame during switching, the channel estimation delay symbol number of the larger sub-frame is n, the channel estimation delay symbol of the smaller sub-frame is m,
and performing channel estimation time domain interpolation calculation on the first n symbols of the subframe with smaller FFT size and the last n symbols of the subframe with larger FFT size, and selectively outputting or not outputting.
8. The OFDM system reception demodulation method as claimed in claim 1, comprising:
and the boundary symbols of the subframes before and after the subframe during switching are substituted according to the subframe to be decoded currently.
9. The OFDM system reception demodulation method as claimed in claim 1, comprising:
may further comprise: and according to the output symbol result of the channel estimation module, balancing the corresponding symbol to balance each symbol of the subframe to be decoded, thereby ensuring the continuity of subsequent decoding.
10. An OFDM system receiver, comprising:
a decoding subframe control module, and a channel estimation module,
wherein, the service layer information and the physical layer signaling are input into a decoding subframe control module,
the decoding subframe control module is used for judging the subframe where the current data of the user is located, outputting a subframe indication needing decoding and outputting the subframe indication to the channel estimation module.
11. The OFDM system receiver of claim 10, comprising:
wherein, the channel estimation module is used for carrying out time domain interpolation:
determining the sub-mode to be entered according to the indication of the current decoding sub-frame and the size relation of the sub-frames before and after the sub-frame during switching;
respectively carrying out time domain interpolation according to the current sub-mode; and
and outputting a time domain interpolation result to perform next processing to obtain a final channel estimation result.
12. The OFDM system receiver of claim 10, further comprising:
a deviation adjusting module, an FFT transforming module, a channel estimating module, a multipath detecting module, a frequency deviation/time deviation estimating module and a balancing module,
wherein, the time domain received signal R is FFT transformed into frequency domain OFDM received symbol R,
the channel estimation module utilizes R to obtain an estimated value H of the frequency domain channel impulse response, R and H are sent to a subsequent equalization module to obtain an estimated value X of a sending signal,
and an estimated value H output by channel estimation is used for a multipath detection module and a frequency offset and time offset estimation module, multipath information output by the multipath detection module is used for filtering the channel estimation module, and an estimation result output by the frequency offset and time offset estimation module is used for deviation adjustment of the front end of the receiver.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910747661.3A CN112398772B (en) | 2019-08-14 | 2019-08-14 | OFDM system receiving demodulation method and OFDM system receiver |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910747661.3A CN112398772B (en) | 2019-08-14 | 2019-08-14 | OFDM system receiving demodulation method and OFDM system receiver |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112398772A true CN112398772A (en) | 2021-02-23 |
| CN112398772B CN112398772B (en) | 2024-04-02 |
Family
ID=74601318
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910747661.3A Active CN112398772B (en) | 2019-08-14 | 2019-08-14 | OFDM system receiving demodulation method and OFDM system receiver |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112398772B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114050956A (en) * | 2021-11-09 | 2022-02-15 | 北京思朗科技有限责任公司 | Wireless signal processing method and wireless signal receiver |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101478338A (en) * | 2008-01-04 | 2009-07-08 | 大唐移动通信设备有限公司 | Multiplex transmission method for public reference signal and special reference signal |
| US20100296594A1 (en) * | 2009-05-19 | 2010-11-25 | Samsung Electronics Co. Ltd. | Apparatus and method for initial synchronization in wireless communication system based on ofdm |
| CN101938620A (en) * | 2010-09-16 | 2011-01-05 | 上海高清数字科技产业有限公司 | Movie-mode video signal processing method and device |
| US20170005761A1 (en) * | 2015-07-01 | 2017-01-05 | Samsung Electronics Co., Ltd. | Transmitting apparatus and receiving apparatus and controlling method thereof |
| EP3116136A1 (en) * | 2015-07-09 | 2017-01-11 | STMicroelectronics (Rousset) SAS | Method for estimating a time-invariant transmission channel, and corresponding receiver |
| WO2017155304A1 (en) * | 2016-03-08 | 2017-09-14 | 삼성전자 주식회사 | Transmitter and subframe arrangement method therefor |
| US20170338978A1 (en) * | 2016-05-23 | 2017-11-23 | Comtech Systems Inc. | Apparatus and methods for adaptive data rate communication in a forward-scatter radio system |
-
2019
- 2019-08-14 CN CN201910747661.3A patent/CN112398772B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101478338A (en) * | 2008-01-04 | 2009-07-08 | 大唐移动通信设备有限公司 | Multiplex transmission method for public reference signal and special reference signal |
| US20100296594A1 (en) * | 2009-05-19 | 2010-11-25 | Samsung Electronics Co. Ltd. | Apparatus and method for initial synchronization in wireless communication system based on ofdm |
| CN101938620A (en) * | 2010-09-16 | 2011-01-05 | 上海高清数字科技产业有限公司 | Movie-mode video signal processing method and device |
| US20170005761A1 (en) * | 2015-07-01 | 2017-01-05 | Samsung Electronics Co., Ltd. | Transmitting apparatus and receiving apparatus and controlling method thereof |
| EP3116136A1 (en) * | 2015-07-09 | 2017-01-11 | STMicroelectronics (Rousset) SAS | Method for estimating a time-invariant transmission channel, and corresponding receiver |
| WO2017155304A1 (en) * | 2016-03-08 | 2017-09-14 | 삼성전자 주식회사 | Transmitter and subframe arrangement method therefor |
| US20170338978A1 (en) * | 2016-05-23 | 2017-11-23 | Comtech Systems Inc. | Apparatus and methods for adaptive data rate communication in a forward-scatter radio system |
Non-Patent Citations (1)
| Title |
|---|
| LUKE FAY: "美国新一代数字电视ATSC 3.0标准技术体系S32物理层介绍", 《广播与电视技术》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114050956A (en) * | 2021-11-09 | 2022-02-15 | 北京思朗科技有限责任公司 | Wireless signal processing method and wireless signal receiver |
| CN114050956B (en) * | 2021-11-09 | 2024-06-04 | 上海思朗科技有限公司 | Wireless signal processing method and wireless signal receiver |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112398772B (en) | 2024-04-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Kim et al. | A new joint algorithm of symbol timing recovery and sampling clock adjustment for OFDM systems | |
| CN101079864B (en) | OFDM Receiver and Equalization Method | |
| US8934330B2 (en) | Method and apparatus for channel estimation | |
| CN101075829B (en) | Method for estimating channel of orthogonal frequency-division multiplexing system | |
| US20080112386A1 (en) | Channel estimation device | |
| WO1999043114A1 (en) | Method and apparatus for signal reception, and medium | |
| CN103873397B (en) | A kind of new joint time domain and frequency domain OFDM receive channel estimation methods | |
| CN110754051A (en) | Wireless communication device, infrastructure equipment and method | |
| WO2010063188A1 (en) | Method and device for filtering orthogonal frequency division multiplexing channel estimate result | |
| JP2010158027A (en) | Method and system for ofdm symbol timing recovery | |
| EP2127286A2 (en) | Methods and apparatus for timing synchronization based on transitional pilot symbols | |
| US20090168930A1 (en) | Methods and Systems for Doppler Estimation and Adaptive Channel Filtering in a Communication System | |
| US8462862B2 (en) | Symbol timing methods and apparatuses using the same in multi-carrier receiving systems | |
| WO2008052732A1 (en) | Subblock-wise frequency domain equalizer | |
| US20100150257A1 (en) | Apparatus and method for estimating timing offset in a wireless communication system | |
| CN102025662B (en) | Channel estimation method and device for MIMO (multiple input multiple output) OFDM (orthogonal frequency division multiplexing) system | |
| US20090097596A1 (en) | Methods and Systems for Impulse Noise Compensation for OFDM Systems | |
| CN112398772B (en) | OFDM system receiving demodulation method and OFDM system receiver | |
| KR20040110341A (en) | TDS-OFDM receiver for using different equalizers according to channel status and method for equalizing of TDS-OFDM receiver | |
| US20080101482A1 (en) | Method and apparatus for refining MIMO channel estimation using the signal field of the data frame | |
| KR20050040615A (en) | Apparatus for estimating channel using training sequence data for digital receiver and method thereof | |
| CN107005515A (en) | Information in WLAN is sent and method of reseptance, apparatus and system | |
| KR100820814B1 (en) | Channel Estimation, Compensation Method and Device in Portable Digital Video Broadcasting Receiver | |
| Cheema et al. | A low complexity fine timing offset and channel estimation algorithm for cooperative diversity OFDM system | |
| JP2003283457A (en) | OFDM communication device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |